Assistance was provided to researchers from NCI and other institutions on the design and statistical analysis of a broad range of laboratory studies including: host cell reactivation studies in the Dermatology Branch to examine whether patients with Alzheimer disease are defective in the repair of DNA damage induced by oxygen radicals; an investigation carried out by the Laboratory of Molecular Carcinogenesis using UV-induced mutations in transfected plasmids to evaluate possible hypermutability of cells from patients with Dysplastic Nevus Syndrome or familial melanoma; a study of transplacental effects of AZT in rodents by the Laboratory of Chemical Carcinogenesis and Tumor Promotion; an investigation of polymorphic variation in the XPC gene by the Laboratory of Molecular Carcinogenesis using a recently identified marker allele with a poly-AT insertion; a study performed in the Laboratory of Genetics of plasmacytoma incidence rates in mice administered the cyclo-oxygenase inhibitor, indomethacin; experiments in the Laboratory of Molecular Biology comparing tumor rates and cell division rates in transgenic and wild type mice; an investigation in the Chemoprevention Branch to examine the effectiveness of certain polyphenols in tea extracts to prevent chromatid damage in cultured cells exposed to ionizing radiation; a study with the Laboratory of Human Carcinogenesis of the p53 mutational spectrum in bladder cancers following treatment with cyclophosphamide; an investigation in the Laboratory of Human Carcinogenesis examining evolutionary conservation of p53 mutational hot spots; an investigation in the Laboratory of Molecular Genetics of the NIA demonstrating an excess of tandem mutations in immunoglobulin genes of PMS2 knockout mice; a study by the Laboratory of Molecular Genetics of the NIA measuring the quantity of various types of oxidative DNA damage in fibroblasts obtained from Cockayne's syndrome patients; a study by the University of Minnesota Laboratory of Environmental Medicine and Pathology of chromosome damage and hormone levels in pesticide appliers.